#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>

struct Haus {
  int links;
  int rechts;
  int hoehe;
};

int main(int argc, char* argv[])
{
	
	std::ifstream ifs;
	std::vector<Haus> haeuser;
	
	if(argc < 2)
	{
		std::cerr << "usage: sky <infile>\n";
		exit(1);
	}
	
	ifs.open(argv[1]);

	if(!ifs)
	{
		std::cerr << "file " << argv[1] << " not found.\n";
		exit(1);
	}

	while (ifs) 
	{
    	int links, rechts, hoehe;
    	ifs >> links >> rechts >> hoehe;
    	Haus haus = {links, rechts, hoehe};
    	haeuser.push_back(haus);
    }
 
	ifs.close();
	
	int n = haeuser.size();
	
	int* xCoord = new int[2*n];
	
	for(int i = 0; i < n; ++i)
	{
		xCoord[2*i  ] = haeuser[i].links;
		xCoord[2*i+1] = haeuser[i].rechts;
	}

	std::sort(xCoord, xCoord + 2*n);

	int sky = 0;
	for(int j = 0; j < 2*n; ++j)
	{
		int hoehe = 0, x = xCoord[j];

		for(int i = 0; i < n; ++i)
		{
			if( x >= haeuser[i].links &&
				x <  haeuser[i].rechts )
			{
				hoehe = std::max(hoehe, haeuser[i].hoehe);
			}
		}
		
		if (sky != hoehe) 
		{
			std::cout << x << "\t" << sky << "\n"
					  << x << "\t" << hoehe << std::endl;
			sky = hoehe;
		}
	}	
	
	delete[] xCoord;				      

}